A bubble chart is a type of chart where each plotted entity is defined in terms of three distinct numeric parameters. Bubble charts can facilitate the understanding of the social, economical, medical, and other scientific relationships.

The entities displayed on a bubble chart can be compared in terms of their size as well as their relative positions with respect to each numeric axis. Since both X and Y axis of the bubble chart are numeric scales, the position of plot is an indicator of two distinct numeric values. The area of the plot depends on the magnitude of a third numeric characteristic. One concern when rendering data with a bubble chart is that the area of a circle is proportional to the square of the radius. So if you scale the radius with your third data point, you will disproportionally emphasize the third factor. To get a properly weighted scale, one should take the square root of the magnitude of this third metric or simply make the data's relationship to the bubble size proportional to circle circumference, as circumference has a linear relationship to the radius. However, many bubble charts are rendered without this correction or do not explicitly state the relationship between the data and bubble size.